Tan Yan, Hutchison Florence N, Jaffa Ayad A
Dept. of Medicine, Endocrinology-Diabetes-Medical Genetics, Medical Univ. of South Carolina, 114 Doughty St., PO Box 250776, Charleston, SC 29425, USA.
Am J Physiol Heart Circ Physiol. 2004 Mar;286(3):H926-32. doi: 10.1152/ajpheart.00757.2003.
Although the primary roles of the kallikreinkinin system and the renin-angiotensin system are quite divergent, they are often intertwined under pathophysiological conditions. We examined the effect of ANG II on regulation of B(2) kinin receptors (B2KR) in vascular cells. Vascular smooth muscle cells (VSMC) were treated with ANG II in a concentration (10(-9)-10(-6) M)- and time (0-24 h)-dependent manner, and B2KR protein and mRNA levels were measured by Western blots and PCR, respectively. A threefold increase in B2KR protein levels was observed as early as 6 h, with a peak response at 10(-7) M. ANG II (10(-7) M) also increased B2KR mRNA levels twofold 4 h after stimulation. Actinomycin D suppressed the increase in B2KR mRNA and protein levels induced by ANG II. To elucidate the receptor subtype involved in mediating this regulation, VSMC were pretreated with losartan (AT(1) receptor antagonist) and/or PD-123319 (AT(2) receptor antagonist) at 10 microM for 30 min, followed by ANG II (10(-7) M) stimulation. Losartan completely blocked the ANG II-induced B2KR increase, whereas PD-123319 had no effect. In addition, expression of B2KR mRNA levels was decreased in AT(1A) receptor knockout mice. Finally, to determine whether ANG II stimulates B2KR expression via activation of the MAPK pathway, VSMC were pretreated with an inhibitor of p42/p44(mapk) (PD-98059) and/or an inhibitor of p38(mapk) (SB-202190), followed by ANG II (10(-7) M) for 24 h. Selective inhibition of the p42/p44(mapk) pathway significantly blocked the ANG II-induced increase in B2KR expression. These findings demonstrate that ANG II regulates expression of B2KR in VSMC and provide a rationale for studying the interaction between ANG II and bradykinin in the pathogenesis of vascular dysfunction.
尽管激肽释放酶 - 激肽系统和肾素 - 血管紧张素系统的主要作用大不相同，但在病理生理条件下它们常常相互交织。我们研究了血管紧张素II（ANG II）对血管细胞中B（2）激肽受体（B2KR）调节的影响。用不同浓度（10^(-9) - 10^(-6) M）和不同时间（0 - 24小时）的ANG II处理血管平滑肌细胞（VSMC），分别通过蛋白质印迹法和聚合酶链反应（PCR）检测B2KR蛋白和mRNA水平。早在6小时就观察到B2KR蛋白水平增加了三倍，在10^(-7) M时出现峰值反应。ANG II（10^(-7) M）刺激4小时后，B2KR mRNA水平也增加了两倍。放线菌素D抑制了ANG II诱导的B2KR mRNA和蛋白水平的增加。为了阐明介导这种调节的受体亚型，将VSMC用10 microM的氯沙坦（AT(1)受体拮抗剂）和/或PD - 123319（AT(2)受体拮抗剂）预处理30分钟，然后用ANG II（10^(-7) M）刺激。氯沙坦完全阻断了ANG II诱导的B2KR增加，而PD - 123319没有作用。此外，在AT(1A)受体敲除小鼠中，B2KR mRNA水平的表达降低。最后，为了确定ANG II是否通过激活丝裂原活化蛋白激酶（MAPK）途径刺激B2KR表达，将VSMC用p42 / p44(mapk)抑制剂（PD - 98059）和/或p38(mapk)抑制剂（SB - 202190）预处理，然后用ANG II（10^(-7) M）处理处理24小时。选择性抑制p42 / p44(mapk)途径显著阻断了ANG II诱导的B2KR表达增加。这些发现表明ANG II调节VSMC中B2KR的表达，并为研究ANG II与缓激肽在血管功能障碍发病机制中的相互作用提供了理论依据。
